The Tamron SP AF 17-50mm F/2.8 XR Di II LD Aspherical (IF) is a good value fast standard zoom lens for APS-C cameras, offering a constant aperture of F2.8 and covering an effective focal length range of 26-75mm. Optical construction comprises 16 elements in 13 groups, and at its minimum focus distance the 17-50mm gives a maximum reproduction ratio of 1:4.5 - not 'true' macro, but usefully close nonetheless. Tamron also makes a newer image-stabilised version of this lens for Canon and Nikon cameras.